[Gvsig_english] calculating centre points of polygon and ascribing coordinates

[Wolfgang Qual]

Hi Simon,
I guess there are more than one possibilities to create centre points
(centroids) for polygon elements:
the first option that comes to my mind is using the sextante plugin.
There is an option "create centroids" for polygon vector layers. x/y
coordinates can be calculated within the "field calculator" in gvSIG
with the two commands x() and y(). You could use the geoprocessing
"spatial join" to add tabular information of a point layer to a polygon
theme.
Hope that helps && regards,
Wolfgang


Am Dienstag, den 24.11.2009, 23:57 +1100 schrieb Simon Cropper
(Botanicus Australia Pty Ltd):
> Hi Everyone,
> 
> Can someone tell me if gvSIG can be used to establish the centre point 
> of a polygon?
> 
> ... and subsequently place the X and Y coordinates in fields in the 
> attribute table of the polygon shapefile?
> 
> ... or alternatively create a point file representing the centrepoint 
> and be able to assign the XY values to that shapefile.
> 
> What I regularly do in alternative programs (OpenJUMP, Kosmo, Sextante) 
> is create a point file showing the centrepoint of a set of polygons 
> (usually representing the sites I have surveyed) and then using ArcView 
> assign the XY coordinate of the points to the northing+easting fields. 
> Reproject into Lat-Long and repeat. These coordinates are used to report 
> the sites locations to government agencies.
> 
> How would you do this in gvSIG?
> 
> Can you use Jpython to do this?